Inkjet printer pens are cartridges installed in inkjet printing systems for storing and dispensing ink onto recording media (e.g., paper). An inkjet printer pen typically includes a pen body for retaining the ink, a printer chip disposed on the pen body for dispensing the ink, and a flexible circuit attached to the body for electrically interconnecting the printing system and the printer chip. During a printing operation, the printing system transmits an electrical signal through the flexible circuit to the printer chip. The signal causes the ink to eject from the pen body onto the recording medium based on the jetting technique used. For example, thermal bubble jetting uses a resistive component that heats up when the electrical signal is received from the printing system. This causes a portion of the ink to volatilize to create a bubble that ejects ink from the pen body. Alternatively, piezoelectric jetting uses a transducer that mechanically ejects ink from the pen body when the electrical signal is received.
The bond between the flexible circuit and the pen body of the printer pen is desirably strong and robust enough to withstand exposure to inkjet inks over extended periods of use. If the bond is attacked by the ink, the flexible circuit may delaminate from the pen body. Additionally, if the conductive components of the flexible circuit are not completely encapsulated with an ink-resistant material, the ink, which typically contains corrosive solvents, may chemically attack the conductive components. This may result in electrical shorts and poor signals, which can render the printer pen inoperable.